Michigan Natural Features Inventory

MSU Extension

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Plants and Animals

Oeneis macouniiMacoun's arctic

Key Characteristics

Wingspan 2.2 inches (5.6 cm). Upper surfaces are orange-brown with narrow black margins; the forewing usually has two black eyespots, and the hindwing has one smaller eyespot. The undersurface of the forewing is essentially orange-brown with two eyespots; the hindwing is mottled blackish brown, usually with a tiny eyespot. Caterpillars are greenish to brown with lateral brownish stripes.

Natural Community Types

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Management Recommendations

Surveys and research are needed to assess this species' abundance, distribution, life history, ecology and threats. Sites at which this species has been documented should be protected and maintained. Adequate suitable habitat at known sites should be maintained including sufficient densities of the species' host plant (once determined). Long-term preservation of the habitats with which this species is associated require maintenance and/or restoration of natural disturbance regimes and other ecological processes that lead to establishment and maintenance of these natural communities.

Active Period

Flight from second week of June to first week of July

Survey Methods

Adults have been observed on mountain maple and bastard-toadflax. Larvae eat grasses and sedges in captivity. Food plants in the wild are unknown other than the larval host plant is a boreal grass. Males are quite pugnacious and territorial. The Macoun's arctic has single generation but is unusual in that the species requires two years to complete a single generation. After eggs are laid in June, larvae feed from July through September. They overwinter during the first year as a small larva. The larva continues feeding the following spring into the fall. They overwinter during the second year as a mature larva. Pupation occurs in the spring and adults fly in late May and early June to early July.